Apparatus for the deposition of a sensitive emulsion for autoradiographs



May 6, 1969 M ORN ET AL 3,442,250

' Filed Nov. 21, 1966 Sheet L of 4 APPARATUS FOR THE DEPOSITION OF A SENSITIVE EMULSION FOR AUTORADIOGRAPHS 1' N VEN 'TORS Ma /7'09 ("o/"02;!

W9! 2 [Ga/f5 may 00 Kzkrz May 6, 1969 CORNU ET AL 3,442,250

APPARATUS FOR THE DEPOSITION OF A SENSITIVE EMULSION FOR AUTORADIOGRAPHS Filed NOV. 21, 1966 Sheet 5% WW; I

May 6, 1969 CQRNU ET AL 3,442,250

APPARATUS FOR THE DEPOSITION OF A SENSITIVE EMULSION FOR AUTORADIOGRAPHS Filed Nov. 21, 1966 Sheet of 4 May 6, 1969 J M CORNU ET AL 3,442,250

APPARATUS FOR THE DEPOSITION OF A SENSITIVE EMULSION FOR AUTORADIOGRAPHS Filed Nov. 21, 1966 Sheet 4 of 4 United States Patent 3,442,250 APPARATUS FOR THE DEPOSITIGN OF A SENSI- TIVE EMULSION FOR AUTORADIOGRAPHS Maurice Cornu, Montgeron, and Louis Khan Van Kien,

Aix-en-Provence, France, assignors to Commissariat a IEnergie Atornique, Paris, France Filed Nov. 21, 1966, Ser. No. 595,673 Claims priority, application France, Nov. 26, 1965,

Int. or. nose 11/00 US. Cl. 118-7 6 Claims ABSTRACT OF THE DISCLOSURE Apparatus for applying an emulsion to plates including a holder for holding a plurality of plates in a flat edge to edge relationship and a reciprocating means including a nozzle and a roller which pass over the plates to apply and smooth the emulsion on the plates. Adjustable cams are provided at each plate which may be positioned to either actuate or not actuate the nozzle as it passes over a particular plate.

This invention relates to an apparatus for the rapid and efficient deposition of a sensitive emulsion on batches of sample-holder plates each containing a radioactive substance to be studied for the purpose of preparing autoradiographs and in particular on batches of histological sections (thin slices of animal or plant tissues) for the purpose of obtaining autohistoradiographs.

As is generally known, the technique of autoradiography (also referred-to as contact radiography or radioautography) essentially consists in applying against a sample-holder plate for the purpose of studying the radioactivity of said plate a sensitive emulsion which may be provided in the state of photographic film. When it has been developed, an emulsion of this kind shows up the radioactivity areas and points of said sample-holder plate, and accordingly constitutes what is known as an autoradiograph.

Autoradiography is frequently employed in physical chemistry but is of special interest both in biology and in medicine in the field of histology (for the study of animal and vegetable tissues) and even in the field of cytology (for the study of cell structure) since it serves to determine the positions of radioactive zones and points of tissues and also of animal and plant cells. In this particular field, autoradiography is more especially referred-to as autohistoradiography.

From the time it was first developed to the present day, and regardless of its applications, autoradiography as a whole has been carried out by a number of different methods for the purpose of solving the problem which essentially consists in applying a sensitive emulsion against a sample-holder plate under study.

The emulsion employed can be that of a photographic film. It is also possible to obtain an emulsion by the simple although somewhat primitive expedient of scraping photographic plates, melting the scrapings and pouring the resulting emulsion onto the sample-holder plate. A further possibility consists in utilizing a castable nuclear emulsion (of a type which is suited for the particles to be detected) which is spread in a thin layer over the sample-holder plate by means of a brush, although the coating thus obtained has the disadvantage of lacking uniformity. Another method consists in spreading the emulsion after the manner of a blood-smear by means of a glass scraper or, better still, by means of a glass rod having a round section in order to avoid the formation of striae in the emulsion. An alternative method consists in pouring a liquid emulsion over glass and then, when 1t "ice has set solid, in withdrawing it and detaching a pellicle or film having a thickness of, say, 0.6 mm. in thickness and employed either alone or in a stack of similar films. After the sample-holder plate under study has been exposed to radiation, the films are separated from each other, mounted again on glass and then developed. An ionizing event which appears in that film which was directly in contact with the sample-holder plate can. thus be followed over a long path through'the other films.

One industrial process of a more highly improved type consists in utilizing sensitive plates known as stripping films. In this process, the sensitive layer is detached from its glass support, then floated on water to hydrate it and endow it with flexibility, the radioactive sample-holder plate to be studied being then immersed beneath this sensitive layer and thus caused to adhere to said layer. The sensitive film coating thus formed is homogeneous and of uniform thickness but this process has the disadvantage of entailing immersion of the sample-holder plate in water, with the result that accurate localization of soluble isotopes in situ is not possible.

Another process consists in dipping the radioactive sample-holder plate under study (for example a thin radioactive histological section) in a liquid sensitive emulsion contained in a vessel. After a predetermined period of time, the sample-holder plate is withdrawn from the emulsion, then hung in a tank in order to eliminate excess emulsion. Intimate contact between the sample-holder plate and the sensitive emulsion is thus achieved, but the thickness of the emulsion coating is not uniform. Furthermore, in the case of soluble isotopes, this method has a disadvantage in that the emulsion contained in the vessel is contaminated.

In accordance with an improved alternative method for pouring a sensitive emulsion onto a glass support plate, the emulsion coating is thinned by subjecting said plate to the action of centrifugal force by means of a turntable and crank or an electric motor. While this method is excellent for the preparation of autoradiographs having a high resolution which are intended to be examined under the electron microscope, it nevertheless has a drawback in that it cannot readily be applied to large batches of radioactive sample-holder plates.

Finally, mention can be made of one improved variant of the method of direct application, in which the sensitive liquid emulsion is spread over the sample-holder plate under analysis by means of a glass rod. This variant consists in replacing the glass rod by a metal roller which is lathe-turned and gaged to a high degree of pr cision. Said roller is provided at one end with an annular guide flange which is intended to slide along one edge of the sample-holder plate during the displacement of the roller and to regularize the spreading of the sensitive emulsion over said sample-holder plate. This method has proved to be one of the most effective up to the present time for the purpose of studying sample-holder plates containing either soluble or insoluble radioisotopes. However, this method also is attended by a number of drawbacks, namely:

(1) It has the defect in the first place of permitting the treatment of only one sample-holder plate at a time;

(2) On account of the sensitivity of the emulsion, this method makes it essential to work in light of very low intensity (red light or green light), thereby complicating the operations involved (the need of undivided attention on the part of the operator, the danger of breakage, the difliculty which is experienced by the operator in becoming accustomed to darkness and then returning to normal lighting conditions, and so forth).

(3) The temperature of application of the sensitive emulsion on the sample-holder plates inevitably varies to an appreciable extent if a large number of sampleholder plates is processed.

(4) By reason of the fact that is a manual process, the thickness of the sensitive-emulsion coating cannot be strictly constant in the case of a large batch of sampleholder plates and, finally,

In spite of the precautions which are taken to regulate the relative humidity (by running water into a sink or wetting the floor or ground), it is not possible to ensure a constant hygrometric state. Although all of the foregoing disadvantages combined do not prove highly detrimental to the qualitative analysis of the radioactivity of sample-holder plates (such as, for example histological sections), such drawbacks in fact make it impossible to make quantitative comparisons between a large number of sample-holder plates.

The disadvantages of all the methods and processes mentioned above have led to the design of the apparatus in accordance with the present invention. This apparams is based on the principle of the last method discussed in the foregoing (hitherto applied solely as a manual process), namely the direct application of a sensitive liquid emulsion on radioactive sample-holder plates (in particular on histological sections) by means of a roller which is machined to very close tolerances. However, the apparatus according to the invention is not subject to any of the disadvantages which have been encountered heretofore in the practical application of this method and, on the contrary, permits of quantitative comparisons in respect of a very large number of radioactive sampleholder plates.

In fact, the apparatus in accordance with the invention has the following characteristics:

(1) It permits the rapid and efficient treatment of a large number of sample-holder plates;

(2) it enables the operator to work almost continuously in normal lighting conditions, the stage of introduction of the liquid emulsion into an emulsion vessel being actually the only moment when darkroom operation is essential;

(3) The temperature is regulated automatically;

(4) The roller which is employed for the purpose of spreading the sensitive emulsion over the sample-holder plates is guided mechanically and its smooth and uniform sliding motion ensures constant thickness of the emulsion coating over said sample-holder plates, even when processing a very large number of such plates at the same time;

(5) the hygrometric state is regulated during the entire period of operation of the apparatus.

Moreover, the apparatus comprises a device for oxidizing the air which surrounds the treated sample-holder plates (by means of hydrogen peroxide or gaseous oxygen) and said oxidation associated with a suitable temperature and relative humidity, assists the removal of impressions produced by cosmic radiations or accidental stray radiations.

More specifically, the present invention relates to an apparatus for the rapid, efiicient and automatic deposition of a sensitive emulsion on batches of radioactive sample-holder plates (such as histological sections, for example) with a view to preparing autoradiographs which permit the possibility of quantitative comparison, said apparatus being constituted by a sensitive-emulsion deposition chamber which is provided with perfect optical insulation from the exterior and in which thermal and hygrometric conditions can be regulated with precision, said chamber being characterized in that it comprises a stationary frame fitted with roller tracks, a removable support panel with retractable cover carrying a series of radioactive sample-holder plates and capable of being locked in position relatively to said stationary frame, a motor-driven carriage adapted to perform a reciprocating movement along said roller tracks, said carriage being adapted on the one hand to carry a sensitive-emulsion distribution unit formed by a vessel provided at the lower end thereof with a nozzle pierced by a calibrated aperture located above said plate and, on the other hand, to draw with it in its motion a roller which is coupled thereto by a solid arm and which is adapted to bear on said radioactive sample-holder plates and to exert a uniform pressure thereon, a system of link-arms being adapted to initiate the discharge of a regulated quantity of sensitive emulsion through the vessel nozzle at the moment when said nozzle passes above each sampleholder plate and, at the end of travel of the carriage, a device for raising and locking the roller and a motionreversing unit for producing the automatic return of the carriage, the mode of assembly of the distribution unit on the carriage being such that the nozzle aperture is located at a distance of a few centimeters in front of the roller so that the emulsion which has been poured onto each sample-holder plate is permitted to spread prior to being subjected to the action of said roller.

The system of link-arms which initiates the discharge of sensitive emulsion through the nozzle comprises a rocker-arm assembly pivotally mounted on a bearing member which is rigidly fixed to the carriage, provision being made at one end of said rocker-arm assembly for a push-button which is adapted to bear on the rod of a piston mounted in the emulsion vessel whilst the other end of said rocker-arm assembly is pivotally attached to a tappet which moves upwards by virtue of the fact that the lower end thereof passes over a runner-wheel as and when the emulsion-delivery nozzle arrives directly above each sample-holder plate, each upward movement of said tappet having the effect of initiating the downward movement of the push-button over a well-defined distance and consequently of initiating the discharge of a well-defined quantity of sensitive emulsion.

Other properties and advantages of the invention will become apparent from the following description in which one embodiment of the apparatus in accordance with the invention is given by way of explanation and not in any limiting sense, reference being had to the accompaying drawings, in which:

FIG. 1 is a external view in perspective of the complete apparatus according to the invention and of its different ancillary components;

FIG. 2 is a rear view of the same unit;

FIG. 3 is a view in elevation showing the interior of the emulsion deposition chamber;

FIGS. 4 and 5 are respectively a partial transverse cross-section and an overhead view of said deposition chamber; and finally,

FIG. 6 is a detail view of the device for lifting and locking the tappet at the end of travel of the carriage.

FIG. 1 is a view looking on the exterior of the emulsion deposition chamber which constitutes the essential object of the invention and which is designated by the reference numeral 1. Said deposition chamber is provided with three lateral access doors which are closed by means of a magnetic latch system and which permit such handling operations as are entailed in servicing, cleaning and inspection (two of the doors referred-to are shown in FIGS. 2 and 3) and is further provided with a top door or hatch 4 through which the emulsion vessel is introduced. An eye-glass 5 provides a view of the chamber through a window 6 (shown in FIG. 3) by means of which the chamber is thermally-insulated from the exterior; a sliding shutter 7 which is rigidly fixed to the base of said eye-glass prevents any light from penetrating into the deposition chamber.

The mechanism employed for driving the carriage which is mounted within the emulsion deposition chamber 1 is constituted by an electric motor (not shown in the figure) which is housed in a frame 8 and by a reduction gear unit 9. The frame 8 comprises a number of different ancillary components (such as a knob 10 for switchin -on the lamp which serves to illuminate the interior of the deposition chamber, a device 11 for controlling the deposition chamber carriage either for continuous operation or for plate-by-plate operation, etc.

The unit which comprises the deposition chamber 1, the frame 8 and reduction gear unit 9 is supported on a wheeled trolley 12 formed of two compartments, namely a compartment 13 (shown on the left-hand side of FIG. 1 and on the right-hand side of FIG. 2) and a compartment 14. Compartment 13 contains a hot water tank 15 (as ShOWn in FIG. 2), a resistance-type heater element 16 and a flow-regulating pump (not shown). The hot'water is circulated through a heating coil which is housed within the deposition chamber 1 and which will be described hereinafter, passes out of the tank 15 through a pipe 17 and is returned to said tank through a pipe 18. A luminous indicator 19 or safety lamp is provided on the front face of compartment 13.

Compartment 14 contains the electronic and electromechanical installation and is provided on the front face thereof (as shown in FIG. 1) with a number of signal lamps 20, switches 21, 22, 23 which control respectively the relay motors, the heating of the tank 15 and the flowregulating pump, fuses 24, 25, 26 which correspond to said switches and a general switch 27. Finally, FIG. 2 shows a thermometer 28 and the end of a panel 29 which serves as a support for the sample-holder plates and which is inserted within the chamber 1. Said support panel will be described in detail below.

FIGS. 3 to 6 which will be described later show the interior of the emulsion deposition chamber 1 which constitutes the essential feature of this invention.

The general principle of the invention is as follows: the support panel 29 with retractable cover (not shown) for carrying radioactive sample-holder plates 31 (such as, for example, histological sections) from which it is desired to obtain autoradiographs by processing within the emulsion deposition chamber 1 is introduced in this latter and is maintained in a stationary position therein; a carriage 32 which is driven in the direction of the arrow F by the motor of the frame 8 (as shown in FIG. 1) carries a vessel 33 which is filled with sensitive emulsion. Said vessel is provided at the lower end thereof with a nozzle 34 pierced by a calibrated aperture and is adapted to draw with it in its motion a roller 35 which is attached to said vessel by means of a solid arm 36. A link-arm system constituted by an assembly of rocker-arms 37, 38 pivotally mounted on a bearing member 40 comprises (at the extremity of the arm 37) a push-button or knob 41, the function of which is to produce action on the rod 42 of a piston (not shown) which is fitted within the vessel 33. A tappet 43 which is pivotally connected at 44 to the arm-38 is adapted to move upwards as the nozzle 34 arrives directly above each sample-holder plate 31 by. virtue of the fact that it passes over a runner-wheel 45 (the apparatus is provided with a whole series of similar runnerwheels, each of which corresponds to one sample-holder plate 31). A

Each upward movement of the aforesaid tappet has the effect of lifting the rocker-arm 38 and lowering the rockerarm 37 and the push-button 41 to a predetermined extent and consequently of initiating the discharge of. a welldefined (and adjustable) quantity of sensitive emulsion through the calibrated aperture of the nozzle 34 onto each sample-holder plate 31. The mode of assembly of the roll er 35 is such that the aperture of the nozzle 34 is located at a distance of a few centimeters in front of said roller in order that the emulsion which has just been poured onto a sample-holder plate 31 may thus be permitted to spread prior to being subjected to the action of the roller. By virtue of the solid arm 36, said roller is applied under high pressure (without rotating about its own axis) against the plate which has just received the sensitive emulsion. When the carriage 32 has reached the end of its travel (on the left-hand side of FIGS. 1 and 2), a reversing unit 46 which is actuated by means of a shoulder 47 its starting point while ensuring that no emulsion is discharged from the vessel and that the roller 35 does not come into contact with the sample-holder plates 31 which have just been treated. The roller is again lowered automatically after it has returned to its starting point.

The plate-coating operation is carried out within the chamber 1 in total darkness, the doors 2, 3, 4 and 30 being closed and the shutter 7 being caused to slide into position so as to seal off the viewing window 6.

The plates 31 which have just been treated are enclosed by means of the retractable cover (not shown) of the support panel 29 and this latter is withdrawn from the chamber 1 through a shielded slit formed in the door 30, the sample-holder plates which are shielded in this manner by said cover being no longer liable to be affected by the action of light. Said sample-holder plates will then be developed and will accordingly constitute the desired autoradiographs.

The displacement of the carriage is carried out on a roller track constituted by guide rails 48 forming part of a frame 49 in which the support panel 29 is fitted.

Said frame 49 is disposed above a heating stage 50 containing a coil 51 which is supplied with hot water from the tank 15 via the pipe 17. The top wall 52 of the heating stage 50 is provided with regulating holes (not shown). The water is circulated continuously through the coil 51. The small dimensions of the chamber 1 make it possible to ensure effective regulation of the temperature which is maintained therein by virtue of a contact thermometer 28. The signal lamps and switches which are shown in FIG. I serve respectively to indicate the moment at which the desired temperature is attained, to start up the motor and to initiate automatic control for a series of sample-holder plates. The coating operation can also be carried out in single-plate sequence by limited and successive displacements of the carriage 32.

The desired relative humidity or prevailing hygrometric state is maintained during the coating of sample holder plates by means of ahumidifying tank (not shown) which is placed at the inlet of the chamber 1 (on the lefthand side in FIGS. 3 and 5). Known volumes of fresh and filtered hydrogen peroxide can be added in said tank so as to produce the favorable oxidation conditions required for the renovation of the emulsions and thus to provide a constant basis of reference at the outlet of the apparatus. Since the initial coating of sample-holder plates 31 is carried out under constant conditions, it will accordingly be possible to perform a quantitative study of the radioactivity of sample-holder plates in respect of several batches of plates. Oxidation can also be performed by gaseous oxygen.

The mechanism of the emulsion deposition chamber 1 further comprises a switch 53 which initiates the motion of the carriage 32 and stops the carriage at the end of its return travel.

The good operation within the chamber 1 and the final result of the operations which consist in coating the sample-holder plates 31 can be checked by means of the eye-glass or telescope 5 which is capable of displacement above the sample-holder plates (positions 5, 5a, 5b). Said telescope is fitted with a red screen and the sighting aperture is retractable by means of a return spring (not shown).

FIG. 4 shows the mode of attachment of the sampleholder plates 31 in their support panel 29. The top surface of these plates is placed at the same level by means of springs 54.

FIGS. 3 and 6 show the devices for lifting and locking the roller 35 and the tappet 43. At the moment when the reversing unit 46 is about to trip (namely when the carriage has reached the end of its outgoing stroke), the member 55 which is secured to the carriage 32 and which had rested up to that time on the top edge of the member 56 (which is secured to the arm 36) comes into abutment with a shoulder-bracket 57, then swings over, with the result that the nose 58 of said member 55 engages in a notch 59 of the member 56. The roller 35 is thus locked in the top position thereof (positions 55a, 56a, 35a) during the return motion of the carriage and is no longer applied against the sample-holder plates.

At the same time, the tappet 43 moves upwards as it reaches a ramp 60 and is immobilized, immobilizing piston rod 42 and its piston with the result that said tappet 43 remains in the raised position and no longer produces action on the runner-wheels 45 while the carriage is returning to its starting position. In consequence, the piston is not moved in vessel 33 and no longer discharges emulsion onto the sample-holder plates. FIG. 6 shows the carriage 32 in the position of return to its initial position (as indicated by the arrow F Accordingly, the tappet 43 is in the raised position and the roller 35 (not shown) is locked in the raised position by virtue of the fact that the member 55 is securely maintained in the notch of the member 56 (positions 55a, 56a). When returning to its initial position, the member 56 comes into contact with a fixed stop 61, the member 55 withdraws from the notch 59 and the roller 35 moves down automatically in readiness for servicing a further batch of sample-holder plates. Each runner-wheel 45 is provided with a flat portion 62, with the result that, if the runner-wheel is caused to pivot through an angle of 180 so that said fiat portion is directed upwards, the tappet 43 does not come into contact with the runner-wheel and is consequently not lifted when it comes directly above said runner-Wheel. In that case, sensitive emulsion is not discharged onto the corresponding plate; the flat portions therefore serve to cut some plates out of circuit. It should be noted that, in the normal position of the runner-wheel (that is to say, when the fiat portion is directed downwards), the dose of sensitive emulsion is a function of the radius of said runnerwheel and of the height of the push-button 41.

The roller 35 is preferably of large diameter and formed of stainless steel. It works without rotating about its own axis, but can be subjected to a movement of rotation should requirements so dictate.

The carriage is drawn by means of a steel cable 63 which passes over a driving pulley 64 which is coupled to the reduction gear unit 9 by means of a bevel drive system. At the other end of the run, said cable passes over two pulleys 65 and 66. The emulsion vessel 33 is provided with a lateral opening 67 for the purpose of filling the vessel if necessary by means of a pipette.

The apparatus in accordance with the invention has a considerable advantage in that the user is permitted to Work under normal lighting conditions during all operations. The only moment when a darkroom is essential is when the vessel has to be filled with sensitive emulsion. Said vessel can contain, for example, 50 g. of emulsion, which makes it possible to process a large number of sample-holder plates without necessitating a further filling operation.

What is claimed is:

1. An apparatus for the rapid, eflicient and automatic deposition of a sensitive emulsion on batches of sampleholder plates of a radioactive substance to be studied, with a view to preparing autoradiographs which permit the possibility of quantitative comparison, and in particular for the deposition of said sensitive emulsion on batches of histological sections (thin slices of animal or plant tissues) with a view to obtaining autohistoradiographs, said apparatus comprising a sensitive-emulsion deposition chamber which is provided with perfect optical insulation from the exterior and in which thermal and hygrometric conditions can be regulated with precision, said chamber comprising a stationary frame fitted with roller tracks, a removable support panel carrying a series of radioactive sample-holder plates and capable of being locked in position relatively to said stationary frame, a motor-driven carriage adapted to perform a reciprocating movement along said roller tracks, said carriage being adapted on the one hand to carry a sensitive-emulsion distribution unit formed by a vessel provided at the lower end thereof with a nozzle pierced by a calibrated aperture located above said plate and, on the other hand, to draw with it in its motion a roller which is coupled thereto by a solid arm and which is adapted to bear on said radioactive sample-holder plates and to exert a uniform pressure thereon, a system of link-arms adapted to initiate the discharge of a regulated quantity of sensitive emulsion through the vessel nozzle at the moment when said nozzle passes above each sample-holder plate and, at the end of travel of the carriage, a device for raising and locking the roller and a motion-reversing unit adapted to initiate the automatic return of the carriage, the mode of assembly of the distribution unit on said carriage being such that the nozzle aperture is located at a distance of a few centimeters in front of the roller so that the emulsion which has been poured onto each sample-holder plate is permitted to spread prior to being subjected to the action of said roller.

2. An apparatus according to claim 1, wherein said system of link-arms which initiates the discharge of sensitive emulsion through the nozzle comprises a rocker-arm assembly pivotally mounted on a bearing member which is rigidly fixed to said carriage, provision being made at one end of said rocker-arm assembly for a push-button which is adapted to bear on the rod penetrating into the emulsion vessel whilst the other end of said rocker-arm assembly is pivotally attached to a tappet which moves upwards by virtue of the fact that the lower end thereof passes over a runner-wheel as and when the emulsiondelivery nozzle arrives directly above each sample-holder plate, each upward movement of said tappet having the effect of initiating the downward movement of the pushbutton over a well-defined distance and consequently of initiating the discharge of a well-defined quantity of sensitive emulsion.

3. An apparatus in accordance with claim 2, characterized in that each runner-wheel is capable of rotating about its own axis and is provided with a flat portion which, when the said fiat portion is directed upwards does not engage said tappet and has the effect of cutting out of circuit the sample-holder plate which corresponds to the said runner-wheel.

4. An apparatus according to claim 1, wherein a heating stage containing a coil supplied by a hot water circulation system is disposed under said stationary frame.

5. An apparatus according to claim 1, wherein a humidifying tank is disposed in communication with said emulsion deposition chamber.

6. An apparatus according to claim 1, wherein a sliding telescope fitted with a red or green screen and having a sighting aperture disposed above the emulsion deposition chamber.

References Cited UNITED STATES PATENTS 1,680,584 8/1928 Angell 118308 X 2,441,701 5/1948 Herz 118-120 3,114,790 12/ 1963 Hanks 1189 X WALTER A. SCHEEL, Primary Examiner.

JOHN P. MCINTOSH, Assistant Examiner.

US. Cl. X.R. 

